The invention relates to the field of optically recordable and readable data carrier disks, the data being recorded in the form of a perturbation of a radiation-sensitive coating, e.g. a thermosensitive coating.
An optical head can comprise a GaAs semiconductor laser, a lens for setting to infinity, one or two anamorphic prisms, a polarization splitting or separating cube, a quarter-wave plate, a focusing lens and a system of servomotors for the focusing on the disk and for following the track.